title: Structural basis for the recognition of mycolic acid precursors by KasA, a condensing enzyme and drug target from Mycobacterium tuberculosis.
abstract: The survival of Mycobacterium tuberculosis depends on mycolic acids, very long α-alkyl-β-hydroxy fatty acids comprising 60-90 carbon atoms. However, despite considerable efforts, little is known about how enzymes involved in mycolic acid biosynthesis recognize and bind their hydrophobic fatty acyl substrates. The condensing enzyme KasA is pivotal for the synthesis of very long (C38-42) fatty acids, the precursors of mycolic acids. To probe the mechanism of substrate and inhibitor recognition by KasA, we determined the structure of this protein in complex with a mycobacterial phospholipid and with several thiolactomycin derivatives that were designed as substrate analogs. Our structures provide consecutive snapshots along the reaction coordinate for the enzyme-catalyzed reaction and support an induced fit mechanism in which a wide cavity is established through the concerted opening of three gatekeeping residues and several α-helices. The stepwise characterization of the binding process provides mechanistic insights into the induced fit recognition in this system and serves as an excellent foundation for the development of high affinity KasA inhibitors.
authors.affiliation: Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Wuerzburg, D-97080 Wuerzburg, Germany; Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schiebel
authors.affiliation: Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400.
authors.forename: Kanishk
authors.initials: K
authors.lastname: Kapilashrami
authors.affiliation: Julius-von-Sachs Institute of Biosciences, Biocenter, Department of Pharmaceutical Biology, University of Wuerzburg, D-97082 Wuerzburg, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Fekete
authors.affiliation: Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400.
authors.forename: Gopal R
authors.initials: GR
authors.lastname: Bommineni
authors.affiliation: Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Wuerzburg, D-97080 Wuerzburg, Germany.
authors.forename: Christin M
authors.initials: CM
authors.lastname: Schaefer
authors.affiliation: Julius-von-Sachs Institute of Biosciences, Biocenter, Department of Pharmaceutical Biology, University of Wuerzburg, D-97082 Wuerzburg, Germany.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Mueller
authors.affiliation: Institute for Chemical Biology and Drug Discovery, Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Tonge
authors.affiliation: Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Wuerzburg, D-97080 Wuerzburg, Germany. Electronic address: caroline.kisker@virchow.uni-wuerzburg.de.
authors.forename: Caroline
authors.initials: C
authors.lastname: Kisker
mesh_terms: D000995:Antitubercular Agents / Q000737:chemistry* / Q000627:therapeutic use; D016503:Drug Delivery Systems; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000627:therapeutic use; D064429:Fatty Acid Synthases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D009171:Mycolic Acids / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014376:Tuberculosis / Q000188:drug therapy / Q000201:enzymology*
chemical_list: D000995:Antitubercular Agents; D004791:Enzyme Inhibitors; D009171:Mycolic Acids; D064429:Fatty Acid Synthases
keywords: Condensing Enzyme; Enzyme Dynamics; Enzyme Inhibitors; Enzyme Mechanisms; Enzyme Structure; Induced Fit Substrate Recognition; KasA; Lipid Synthesis; Mycobacterium tuberculosis; Phospholipid